The present invention relates to a pneumatic tire, more particularly to a tread pattern capable of improving high-speed running performance, especially steering stability during running in a racing circuit, as well as wet performance.
Japanese Patent Application Publication No. 2009-101785 discloses a pneumatic tire having a tread pattern shown in FIG. 5, wherein a circumferential groove (a) is disposed on each side of the tire equator Co, and main oblique grooves (b) and auxiliary oblique grooves (c) are disposed axially outside the circumferential groove (a) and arranged alternately in the tire circumferential direction. The main oblique groove (b) and auxiliary oblique groove (c) each have an axially outer end positioned axially outside the tread edge E1.
The axially inner end of the auxiliary oblique groove (c) is located far from the circumferential groove (a), but the axially inner end of the main oblique groove (b) is located very close to the circumferential groove (a).
As a result, the land portion (d) between the circumferential groove (a) and tread edge E1 is considered as being circumferentially divided into blocks (f) in practice.
Since the axially inner part (b1) of the main oblique groove (b) is steeply inclined with respect to the axial direction, the block (f) has a narrow-angled part (fe) between the circumferential groove (a) and the steeply-inclined inner part (b1).
Therefore, it is difficult to increase the rigidity of the land portion (d) to a sufficiently high level to further improve the dry grip performance.
Thus, there is room for improvement in high-speed running performance, especially steering stability during running in a circuit.
As to the wet performance, on the other hand, since the axially inner end of the main oblique groove (b) is not opened to the circumferential groove (a), there is room for improvement in the drainage.